UN R90 Supplement 9 (02 series) · UNECE Regulation No. 90 (ECE R90) — Uniform provisions concerning the approval of replacement brake lining assemblies, drum-brake linings and discs and drums for power-driven vehicles and their trailers.
UN R90 — Supplement 9 to the 02 series of amendments
Supplement 8 → 9
- What changed
- Item (b) of the Annex 7a grouping criteria now ends “or, in case of drum brakes, of only one brake shoe”.
- A new Table 2 in Annex 7a gives 3 area groups for brake shoes: A (≤21 cm2), B (> 21 ≤ 54 cm2) and C (> 54 cm2).
- The definition of friction material area now refers to Figure 1 and a new Figure 2.
- Why
- Annex 7a did not provide explicit directions for the grouping of brake shoes.
- Clear instructions about grouping criteria for brake shoes were necessary to allow brake shoes manufacturers to proceed with the homologation according to this Regulation.
- The amended proposal is meant to specify area groups fully aligned with the brake shoe product range currently on the market.
Q1What changed7 changes
Friction material area for drum brakes (Annex 7a, para. 1.)
Item (b) of the grouping criteria now ends “of only one side of the brake calliper or, in case of drum brakes, of only one brake shoe.” Before, it ended “of only one side of the brake caliper.” The definition of friction material area now says “see the red cross-hatched area, Figure 1, Figure 2”. Before, it referred to Figure 1. A new Figure 2 is added.
Area groups for brake shoes (Annex 7a, Table 2)
Annex 7a now says “3 area groups are foreseen, as in Table 1 (for brake pads) and in Table 2 (for brake shoes)”. Before, it referred to Table 1. The new Table 2 gives these brake lining areas in cm2: group A ≤21, group B > 21 ≤ 54 and group C > 54.
Q2Why it changed
- Proposed by
- Expert from Italy
- Working party
- GRVA, 12th session (January 2022)
Reasons
Information was found to be missing while implementing UN Regulation No. 90. The purpose of Annex 7a is to specify the grouping criteria of the brake lining assemblies for vehicles of Category L. But Annex 7a does not provide explicit directions for the grouping of brake shoes.
Sources (2)
“Information have been found to be missing while implementing UN Regulation”
“Despite of its purpose, which is to specify the grouping criteria of the brake lining assemblies for vehicles of Category L, Annex 7a does not provide explicit directions for the grouping of brake shoes.”
Paragraph 2.2.3. defines a “brake shoes assembly” as a type of brake lining assembly. Therefore, clear instructions about grouping criteria for brake shoes (as already done for brake pads) are necessary. Their aim is to allow brake shoes manufacturers to proceed with the homologation according to this Regulation.
Sources (2)
“Paragraph 2.2.3. defines "Brake lining assembly" as a component of a friction brake which is pressed against a drum or disc, respectively, to produce the friction force and a “brake shoes assembly” as a type of brake lining assembly.”
“it is necessary to provide clear instructions about grouping criteria for brake shoes (as already done for brake pads) to allow brake shoes manufacturers to proceed with the homologation accordingly to this Regulation.”
Proposer's reason (informal document GRVA-12-16)
At the 11th session of GRVA, some observations were raised about the applicability of the 3 area groups in Table 1 to brake shoes. The amended proposal is meant to specify area groups fully aligned with the product range currently on the market. Group A is for small size vehicle brake shoes, group B for medium size and group C for big vehicle brake shoes.
Submitted by the expert from Italy. Working party adoption: ECE/TRANS/WP.29/GRVA/12, para. 90.
Sources (5)
“some observations were raised concerning the applicability of the 3 area groups indicated in Table 1, as far as grouping criteria for brake shoes are concerned.”
“This proposal is meant to specify area groups fully aligned with product range currently on the market”
“GROUP A, relative to small size vehicle brake shoes,”
“GROUP B, relative to medium size vehicle brake shoes,”
“GROUP C, relative to big vehicle brake shoes.”
Proposer's reason (informal document GRVA-12-16)
The considerations for the groups are based on the range of brake shoes currently produced by main brake shoes manufacturer. This range covers more than 98% of the brake shoes EU market used on L category vehicles. In the current catalogue, the brake shoe areas range from 9 cm2 to 80 cm2. Group B is centred about the average value of the areas, and its amplitude corresponds to 2.00 standard deviations.
Submitted by the expert from Italy. Working party adoption: ECE/TRANS/WP.29/GRVA/12, para. 90.
Sources (3)
“The following considerations are based on the range of brake shoes currently produced by main brake shoes manufacturer, covering more than 98% of the brake shoes EU market used on L cat vehicles.”
“On the basis of the current catalogue, the brake shoes area rank from 9cm2 to 80cm2.”
“is centered about the average value of the areas while its amplitude corresponds to 2.00 standard deviations”
Proposer's reason (informal document GRVA-12-16)
The brake shoes are originally sized by the vehicle manufacturers, based on vehicle performance and mass. So it is reasonable to say that all the average kinetic energy vehicles will be included in Group B. It is also reasonable to say that the lower energy ones will be in Group A and the high kinetic energy vehicles in Group C.
Submitted by the expert from Italy. Working party adoption: ECE/TRANS/WP.29/GRVA/12, para. 90.
Sources (3)
“Considering that the brake shoes are originally sized from the vehicle manufacturers (based on vehicle performance and mass)”
“It is therefore reasonable to say that all the average kinetic energy vehicles will be included in Group B, the lower energy ones will be included in Group A”
“while the high-kinetic energy vehicle will be in Group C”
Document trail
- 2021-07ProposalECE/TRANS/WP.29/GRVA/2021/29Proposal by the expert from Italy
- —Amended in sessionGRVA-12-16Amendments to ECE/TRANS/WP.29/GRVA/2021/29
- —Working party adoptsECE/TRANS/WP.29/GRVA/12GRVA session report, para. 90
- 2022-04Sent to WP.29ECE/TRANS/WP.29/2022/82Text that GRVA sent to WP.29 and AC.1
- 2022-06WP.29 adoptsECE/TRANS/WP.29/1166Adopted at the 187th session (session report, para. 182)
- 2023-01-04In forceC.N.487.2022.TREATIES-XI.B.16.90UN depositary notification
Q3Who is affected
Vehicle manufacturer
- No direct action for this role.
Component supplier
- Check which Table 2 area group each of your brake shoes for category L vehicles falls in.
- In the case of drum brakes (category L), group by the friction material area of only one brake shoe.
Technical service / Approval authority
- In the case of drum brakes (category L), check that brake shoes are grouped by the Table 2 area groups.
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ⓘ This report gives advice only. It is not legal or type-approval advice.